At physiological concentrations, acetaldehyde forms non-enzymatic adducts with hemoglobin which are stable to extensive dialysis for several days. The amount of stable hemoglobin adducts formed is a function of the concentration and number of exposures to acetaldehyde. The reaction of acetaldehyde with hemoglobin A produces chromatographic variants, some of which migrate in the HbA(1a-c) region. Valine, glucosyl-valine, lysine, glucosyl-lysine and tyrosine residues of globin are the sites of reaction. The acetaldehyde modified amino acid residues appear to exist in interconvertible conformations, only one of which is reducible by sodium borohydride. The amount of these adducts appears to be significantly elevated in hemoglobin from alcoholics as compared with normal volunteers. The present proposal utilizes biochemical techniques to define the specific sites of reaction of acetaldehyde with hemoglobin and the structure of the acetaldehyde adduct with valine, lysine, their glucosyl adducts and tyrosine. Studies will be performed in animals to define the biological on and off rates of adduct formation. Animal tissues will be studied to determine whether acetaldehyde adducts occur in sites other than hemoglobin such as plasma proteins, lens, nerve, muscle, liver or bone. Human studies will define the off rate of acetaldehyde adducts. An attempt to develop alternative assays including a radioimmunoassay for these adducts will also be undertaken. These studies will provide insight into the chemical nature of acetaldehyde adducts, whether they are involved in the pathophysiology of alcoholism, and whether they may be useful markers for alcohol consumption.